. Wooden box and crate construction . reduced by substituting plywood forveneer, since it offers more resistance to puncturing. Ifwarped lumber or veneer is used, initial stresses are produced BOX DESIGN 47 when such material is forced to a-ssume the proper shape inassembling the box. Such initial stresses decrease the amountof strength remaining for resisting the hazards of made of such material may also be somewhat mis-shapen. Moisture Content^—The moisture content of the materialused in constructing boxes influences their strength greatly,and in various ways. An abnormal amoun
. Wooden box and crate construction . reduced by substituting plywood forveneer, since it offers more resistance to puncturing. Ifwarped lumber or veneer is used, initial stresses are produced BOX DESIGN 47 when such material is forced to a-ssume the proper shape inassembling the box. Such initial stresses decrease the amountof strength remaining for resisting the hazards of made of such material may also be somewhat mis-shapen. Moisture Content^—The moisture content of the materialused in constructing boxes influences their strength greatly,and in various ways. An abnormal amount of moisture inbox material causes the points of the nails to pull more easilyfrom the wood, the heads to pull through the wood, and theshanks of the nails to shear out at the ends of the boxes made of green or wet material subsequently dryout, the nails become loose and pull easily. The boards alsosplit and check because the nails resist the shrinkage, whichis the normal result of drying. Variations and changes in the. Fig. 13—Effect of shrinkage on strapped boxes. Boxes made and strapped at a 30 per cent moisture content; the boxes were photographed after drying out to 10 per cent moisture Content. amounts of moisture contained in box lumber affect thestrength of a box, as indicated by the results of tests givenin figure 12. The moisture content of box material has a very greatinfluence on the maintenance of the strengthening effect ofstrapping and wire bands. If shrinkage occurs after strappingis nailed on, the strapping buckles between the nails. (Seefigure 13.) Straps with ends joined by some sealing or See page 15 for general discussion of moisture content. 48 WOODEN BOX AND CRATE CONSTRUCTION clamping device often become so loose through shrinkage ofthe wood that unless nailed in place they will easily slip ofifthe box. Inspectors have reported that large quantities ofstraps which have slipped off boxes, with the seals unbroken,are at times left in freig
Size: 2164px × 1155px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorforestpr, bookcentury1900, bookdecade1920, bookyear1921
